Hybrid energy system and method

ABSTRACT

Various embodiments include systems and methods of operating a hybrid energy system that includes a gas-turbine generator configured to provide a full-load power output and a storage device configured to store energy. The hybrid energy system includes a generator step-up transformer, wherein the gas-turbine generator and the storage device are electrically co-located on a low side of the generator step-up transformer. Methods of operation include controlling power output from the storage device and/or the gas-turbine generator during scheduled and unscheduled grid power demands to achieve economic and environmental performance advantages.

CLAIM OF PRIORITY

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/497,685 entitled “HYBRID ENERGY SYSTEM AND METHOD” filedSep. 26, 2014, which claims the benefit of priority of U.S. ProvisionalPatent Application Ser. No. 61/882,899, filed on Sep. 26, 2013 and U.S.Provisional Patent Application Ser. No. 61/898,866, filed on Nov. 1,2013, all three of which are herein incorporated by reference in theirentirety.

BACKGROUND

Energy facilities are designed to provide energy to an electric grid ina reliable manner One example of an energy facility includes a gas firedgeneration system, such as a gas turbine generator (GTG), configured toprovide energy to the electric grid while maintaining the frequency andvoltage of the electric grid within acceptable limits, such as limitsset by a government body, a regulatory body, transmission gridoperations, or an energy facility. Electric grid demands changedepending on a number of factors including weather, market demands, andother reliability driven events. The energy facility is typicallydesigned to ramp up, including starting, or ramp down in response tothese factors.

One example of an energy facility includes a combined cycle gas turbine(CCGT) configured to remain on-line a substantial majority of the timein order to respond to the electric grid reliability factors.

SUMMARY

The following is a brief summary describing a system and method tocombine electric storage and gas-fired generation into a single hybridenergy facility when viewed from the grid. The hybrid design isespecially well suited for locations near load centers as it displacesthe need to have thermal generation running in the local area on analmost continuous basis to provide the required inertia, energy andother services necessary to ensure grid reliability. The hybrid facilitycan provide the necessary reliability with a significantly reducedemissions profile and at a lower overall cost. The fast acting hybridfacility also has excellent power conditioning and ramping capabilitieswhich are vital to supporting the grid as well as the continued growthof renewables such as wind and solar. The hybrid can be less onerous tothe site than new gas only projects of equivalent size.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. The drawingsillustrate generally, by way of example, but not by way of limitation,various embodiments discussed in the present document.

FIG. 1 is a block diagram of one example of a hybrid energy system,according to the present disclosure.

FIG. 2 is a plot of one example of a hybrid energy system start profile,according to the present disclosure.

FIG. 3 is a plot of one example of an operation of the hybrid energysystem, according to the present disclosure.

FIG. 4 illustrates a transient response of a hybrid energy system andgas turbine only system, according to the present disclosure.

FIG. 5 is an example hybrid generation grid support system response timeplot.

FIG. 6 is a process flow diagram of an example Hybrid Management Systemfeed forward process based on a day ahead expected delivery schedule.

FIG. 7 is a process flow diagram of an example Hybrid Management Systemprocess for providing power according to an expected delivery schedule.

FIG. 8 is a plot of example ramp trajectories that may be implemented ina hybrid energy system.

FIG. 9 is a process flow diagram of an example Hybrid Management Systemfeedback process for providing real-time delivery of power.

DETAILED DESCRIPTION

The present inventors have recognized, among other things, that aproblem to be solved can include reducing response times of a GTG, suchas starting, ramping up, or ramping down, to an electric gridreliability factor. One example of an energy facility includes a simplecycle GTG that is most commonly configured to be in a stand-by state,ready to start and operate only when called upon, resulting in a lesserresponse capability to electric grid reliability factors. Energyfacilities are typically designed to meet some combination of energy andelectric grid reliability needs. Tradeoffs are typically made betweenone or more of size, amount of energy that can be produced, efficiency,time to start, rate of capability to ramp output up or down, ability tooperate at low power output levels relative to maximum output levels,and ability to provide products that support reliability, such asancillary services and reserves.

Ancillary services typically include operating reserves that are setaside for specific types of reliability events including, but notlimited to: Regulating reserves—typically regulation is provided bysynchronized generation and is dedicated to maintaining the frequency ofthe electric grid; Spinning reserves—typically provided from theunloaded portion of a synchronized generator, spinning reserves areimmediately available to arrest a frequency excursion; Non-spinningreserves—typically provided by off-line generating units in a stand-bystate that can start and ramp up their energy output within 10 minutesto restore electric grid frequency after it has been arrested byspinning reserves; Voltage support—typically provided by on-linegeneration, synchronous condensers and inverter systems, voltage supportsystems maintain electric grid voltage and reactive load (VAR); andBlack-start—typically provided by energy facilities with the capabilityto start and generate electricity without aid from the electric grid.These units are available to re-start the electric grid followingblack-out conditions. The quality of these operating reserves has adirect impact on electric grid reliability.

In an example, the present subject matter can provide a solution to thisproblem, such as by a hybrid energy system that aggregates andintegrates a storage system, such as a battery and a GTG, to combine thefeatures of each into a responsive system. For example, the presentsubject matter provides hybrid energy systems configured to beresponsive, so as to provide higher quality reserves by at least one ofspeed, rate, magnitude, and duration of the response a to transientevent. By providing a responsive hybrid energy system, the presentsubject matter economically reduces response times of a GTG.Economically reducing response times includes at least one of reducingthe overall start-up time or ramp time to the desired load, reducing thetime to respond to a frequency disturbance, as described herein, andreducing the production of pollutants during start-up or ramping,resulting in higher quality reserves. In another example, the presentsubject matter includes a battery having substantially immediatedischarge capability and a GTG that can rapidly start and supplement thepower output of the battery in the matter desired by electric gridoperators. In another example, the present subject matter can provide asolution to this problem, such as by a hybrid energy system having a GTGconfigured to have a fast-start, fast ramp capability in combinationwith a substantially immediate discharge capability from a storagedevice, such as a battery. Such examples provide the benefit of reducingthe time the hybrid energy system responds to a change in electric griddemand.

The present inventors have further recognized that another problem to besolved can include reducing an amount of pollutants produced by anenergy facility (such as a CCGT) remaining on-line to respond toelectric grid demands. In one example, the present subject matter canprovide a solution to this problem, such as by a hybrid energy systemthat includes a storage system, such as a battery, that is synchronizedand ready to respond to electric grid reliability factors, ramp up, andprovide substantially immediate energy for a limited period of time anda GTG in a stand-by state (e.g., off-line but substantially immediatelyready to start) which significantly reduces or eliminates the productionof pollutants when the GTG is not designated to provide energy to theelectric grid. An off-line GTG is considered to be a GTG in a non-powerproducing state. Benefits of such an example include staging the GTG fora fast-start response to an electric grid demand while reducing oreliminating the pollutant profile of the hybrid energy system when notproviding energy to the electric grid.

The present inventors have further recognized that another problem to besolved can include reducing the cost of providing reliability and energyservices produced by an energy facility. Hydro-carbon based energy, suchas burning or combusting of natural gas, can be an expensive,non-economic energy product approach, as compared to alternative formsof energy production. The present subject matter, in one example, canprovide a solution to this problem, such as by leveraging market shiftsto store energy in a storage device configured to substantiallyimmediately discharge the energy to aid in the fast-start capability ofthe GTG, as well as provide energy to the electric grid in response toelectric grid demands. In an example, the present subject matter canprovide a solution to this problem, such as by remaining off-line so asto not produce energy when it is non-economical.

FIG. 1 shows one example of a block diagram of a hybrid energy system10, including a generator step-up transformer 16, a GTG 12, and astorage device 14. The step-up transformer 16 is configured, in anexample, to convert the output of the GTG 12, the storage device 14, orboth, to a higher voltage prior to being provided to an electric grid20, where electric grid impedance is represented by block 18. AlthoughFIG. 1 shows only one GTG 12 and one storage device 14, examples are notso limited. For example, the hybrid energy system 10 can include one ormore GTG 12 coupled to one or more storage devices 14. That is, the GTG12 can be coupled to a plurality of the storage devices 14 or aplurality of the GTGs 12 can be coupled to a plurality of the storagedevices 14, such as an energy storage bank. As shown, the storage device14 is coupled to the GTG 12 and each are electrically co-located on alow-side 22 of the generator step-up transformer 16. In an example, theelectrical co-location of the GTG 12 and the storage device 14 permitsthe hybrid energy system 10 to be operated as either a single generationor non-generation resource (e.g., storage) with an operating range fromthe full negative capacity of the one or more storage device to thecombined positive capacity of the storage device and the GTG. Asdiscussed herein, electrically co-locating the GTG 12 and the storagedevice 14 allows for the faster responding inverter-rectifier 15 of thestorage device 14 to aid the GTG response time in the event of electricgrid frequency transients. Likewise, the same electrical co-locationallows the inverter-rectifier 15 ability to ride through transients inelectric grid voltages provided that the GTG 12 is on line.

In an example, the system 10 is located in multiple geographiclocations, such that the GTG 12 can be separated from storage device 14.That is, the footprint of the hybrid energy facility is not limited to asingle contiguous location, provided that the GTG 12 and the storagedevice 14 are electrically co-located at the same point on the electricgrid 20 (e.g., the low side 22 of the step-up transformer 16).

GTG

The GTG 12 is configured to provide a power output, including up to afull-load power output. In an example, the GTG 12 includes a turbine,such as an aero-derivative or heavy-duty gas turbine having thefull-load power output anywhere from about 10 MW to about 350 MW ormore. The GTG 12, in an example, is configured for a fast start, such asabout 20 minutes or less, about 10 minutes or less, about 5 minutes orless, or about 2 minutes or less. Starting the GTG 12 includes from thestand-by state (e.g., off-line but substantially immediately ready tostart) to a desired load of the GTG, including up to full-load poweroutput. Off-line includes, in an example, a non-power producing state ofa GTG. In an example, the stand-by state of the GTG 12 includes the GTG12 off-line, but substantially immediately ready to start. In anexample, the GTG 12 includes an auto-start feature configured to startthe GTG 12 in response to a frequency disturbance event. That is, in anexample the hybrid energy system 10 is configured to provide the GTG 12droop-like capability when off-line in response to a frequencydisturbance event, such as a transient or decay in frequency. Thisexample also allows for the inverter-rectifier 15 of the storage deviceto supply voltage support with the GTG 12 in the stand-by state. In anexample, the GTG 12 can include a clutch between the gas turbine and thegenerator, so as to provide substantially synchronous condensing. Such aconfiguration permits the system 10 to provide a substantiallycontinuous and a substantially immediate response to electric gridtransient voltage events, which can be accomplished without burning fuelor creating combustion emissions.

In some embodiments, the GTG 12 may implement super-low minimum power(Pmin) technology that may enable the GTG to maintain a gross Pmin of nogreater than the total hybrid facility parasitic load, such as about 0.5MW. By deploying the super-low Pmin technology in the GTG 12, the hybridfacility can be capable of having the gas turbine online servingparasitic loads while the net output of the facility is approximatelyzero MW or even negative, such as receiving some power from the grid forcharging one or more batteries. This configuration allows for animmediate (e.g., “spinning reserve”) response from the entire facilitywithout putting uneconomic or unwanted energy to the grid. Thus, thisconfiguration enables the GTF to be online and synched to the gridwithout affecting the net power output to the grid.

Storage Device

The storage device 14 is configured to store energy. In an example, thestorage device 14 includes a battery, such as a fast acting batterysystem, including an inverter-rectifier 15 to convert direct current(DC) energy being discharged from the storage device 14 to alternatingcurrent (AC) energy required by the electric grid 20 or AC energy beingproduced from either the electric grid 20 or the GTG 12 into DC energystored in the storage device 14. In an example, the inverter-rectifier15 is, but is not limited to, a four quadrant inverter. In an example,the storage device 14 is configured to respond or provide power (e.g.,at least a portion of the stored energy) in about 60 seconds or less,about 30 seconds or less, about 10 seconds or less, about 5 seconds orless, about 2 seconds or less, 1.0 seconds or less, 0.5 seconds or less,or 0.1 seconds or less. In an example, the storage device 14 andassociated inverter-rectifier is configured to receive (e.g., charge)and provide (e.g., discharge) energy.

In an example, the storage device 14 is configured to be charged by theelectric grid 20, such as when electric grid market costs are lower thanthe cost of producing energy with the GTG 12 (e.g., the GTG chargingcost). The grid market cost is at least one of the environmental,monetary, and other costs associated with obtaining power from theelectric grid 20 and the GTG charging cost is at least one of theenvironmental, monetary, and other costs associated with producing powerat a set fuel cost and heat rate of the GTG. In another example, thestorage device 14 is configured to be charged by the GTG 12 when theelectric grid market costs are more expensive than the cost of producingenergy with the GTG 12. In an example, both the electric grid 20 and theGTG 12 can be used to charge the storage device 14. In an example, aportion or all of the GTG 12 output is converted to DC and delivered toa DC bus of the storage device 14 and the inverter-rectifier 15 to allowfor further improvement in the primary frequency response, as describedherein. Primary frequency response includes, for example, a responsewithin about 30 seconds of the event that is meant to arrest a frequencydisturbance. The GTG 12 includes, in an example, frequency response autostart capability, such that when the GTG 12 is in the stand-by state theoutput of the storage device 14 is substantially immediately increasedand the GTG 12 auto starts in the event of an electric grid frequencydecay or transient. In an example, the hybrid energy facility 10includes a waste heat recovery generator. The waste heat recoverygenerator, in an example, is based upon the Organic Rankine Cycle andsubstantially all output is converted to DC and flows to the DC bus ofthe storage device inverter-rectifier 15.

In an example, the storage energy can be any capacity as long as thestorage device 14 is capable of maintaining and providing the minimumstored energy necessary to provide primary frequency response during thetime period while the GTG 12 is started and ramped to a desired load,such as an operator load set-point, up to and including full-load. In anexample, the storage device 14 has an energy storage capacity of atleast about 5% of the full-load power output up to about 100% of thefull-load power output of the GTG 12. Further, the storage device 14, inan example, includes a plurality of inverter-rectifier 15 having atleast 10% of the full-load power output of the GTG 12.

In another example, the storage device 14 has an energy storage capacityapproximately equal to or greater than the full-load power output of theGTG 12. That is, the storage device 14 at least has, in an example,approximately the same immediate power discharge capability as the GTG12 when started and fully loaded. As described herein, the storagedevice 14 provides a short-term substitution of the GTG 12 fullgeneration capacity. In an example, the stored energy capacity of thestorage device 14 is at least about 30 minutes, about 1 hour, about 1.5hours, about 2 hours, or about 4 hours or longer of power discharge ator beyond the full-load power output of the GTG 12.

Hybrid Management System (HMS)

The hybrid energy system is governed by an HMS which ensures that thefacility can deliver the desired product at the desired time in acost-efficient mariner. The HMS may receive its Real Time (RT) dispatchinstructions directly from the Operator. The Operator may be locatedremotely from the hybrid facility and may be a function of any entity,or automated system as may be defined in an off-take agreement. It maybe the duty of the Operator to respond to the economic and reliabilityinstructions from the grid operator. The HMS may be configured to followthe instruction as received by the Operator and ensure that the netoutput of the plant is at the instructed point at the instructed time.The HMS may do so in a manner that considers the remaining daily needsand economics. The HMS may integrate market knowledge, operationalknowledge, or both to prepare the system so that it is positioned toefficiently respond to signals from the Operator in accordance with anyoff-take agreement that might exist.

The HMS may include feed-forward and feedback loops to govern at leastone of the facility conditions, including state of charge (SOC) of thebattery, start and stop the gas turbine, and govern the ramp rate of thenet plant output. The HMS can determine a number of factors, including:Excepted Delivery Schedules (EDS) from the market awards and schedulesprovided by the Operator; the timing for battery charge based uponmarket or contract prices; and the least cost method to deliverscheduled energy by optimizing information from the life-cycle costs andoperational limits envelopes against the EDS and required ramp rates byproduct type. In this way, the HMS may function much like the embeddedsoftware in a hybrid vehicle when it responds to a signal from theaccelerator or brake, except that the HMS has more anticipatory logic.The HMS will make decisions and issue instructions to start and stop theGTG, charge the battery, and ramp the plant at specified ramp rates. TheHMS can start and stop the gas turbine as required in such a way as tokeep the output linear as required.

The hybrid energy system may also include power electronics associatedwith power conversion and balance of plant equipment, including the ACportion of the plant, controls, switchgear, and the like, some or all ofwhich may be controlled or partially controlled by the HMS.

Configurations

In various embodiments, both the gas turbine and the battery inverterare connected on the low side of the same Generator Step-Up (GSU)transformer. This enable an immediate response from the inverter to gridfrequency disturbances, and thus enables the GTG 12 to have increasedride-through capability during grid frequency disturbances when the GTGis operating in a minimum power mode.

In an example, a portion or all of the gas turbine output may beconverted to direct current (DC) and delivered to a DC bus of thebattery inverters to allow for even further improvement in the primaryfrequency response. Additionally, the gas turbine may be equipped with afrequency-response auto-start capability for those instances when theGTG 12 is not running The start times for the gas-fired turbinegenerator may be integrated into the ramp rate of the energy storagesystem such that the gas-fired generation start time is non-apparent tothe total facility output. Maintaining a gas-fired generation gross Pminof no greater than the total facility parasitic load allows thegas-fired generation to be online and available for immediate responsewithout affecting the hybrid facility net output and without requiringmarket uplifts for minimum load cost recovery.

The configurations described below are examples that use the system asdescribed relative to FIG. 1.

Enhanced GTG (EGT)

In an example, the hybrid energy system 10 is configured to use thestorage device 14 to enhance the operational characteristics of the GTG12. For example, the stored energy capacity of the storage device 14 isused as spinning reserve and is used to provide initial primaryfrequency response while starting the GTG 14 from the stand-by state upto a desired load output of the hybrid energy system (e.g., operatorload set-point), such as up to and including full-load power output. Inan example, stand-by state includes a non-fuel burning mode, in whichlittle fuel to no fuel is combusted. During periods when the electricgrid 20 is operating within its normal operating limits, such asoperating limits for frequency or voltage established by transmission ordistribution operators, the GTG 12 is configured to remain in thestand-by state (e.g., off-line, but ready to substantially immediatelystart). In such an example, the storage device 14 remains on-line, andprimary transient protection is provided by the stored energy andinverter-rectifier 15 of the storage device 14. For example, the hybridenergy system 10 may be configured to start the GTG 12 from the stand-bystate to the desired load output, such as the full-load power output, inabout 20 minutes or less, about 10 minutes or less, about 5 minutes orless, or in a about 2 minutes or less.

When an electric grid transient occurs, the stored energy of the storagedevice 14 is used for transient protection, such that the GTG 12 starts,such as substantially instantaneously and at least a portion of a storedenergy of the storage device 14 is transferred to the electric grid. Inthe instance where the electric grid 20 requires additional economicenergy, the gas fired generator can be started and loaded without theuse of the storage device 14.

The storage output of the storage device 14 does not need to be additiveto the GTG 12 output, but rather provides (e.g., substantiallyinstantaneously) output until the GTG 12 can deliver the necessaryoutput to provide a substantially similar ramp curve as the GTG 12alone, as described herein. That is, the storage device 14 can be slavedto a total output of the hybrid energy system 10 such that the storagedevice 14 discharges the difference between the desired expected outputif the GTG 12 was initially synchronized and the actual GTG output, on anet basis. For example, the EGT configuration enhances the GTG 12 suchthat the hybrid energy system is operated in a smooth, continuousfashion with a single monotonically increasing energy supply curve.

In an example, as opposed to being in the stand-by state, the GTG 12 isconfigured to operate at a minimum power output of less than about 5%,less than about 3%, or less than about 1% of the full-load power outputof the GTG 12. The minimum power output is the minimum output at whichthe GTG 12 can stably operate. In such a configuration, for example, thestorage device 14 has a stored energy capacity of at least about 5% ofthe full-load power output up to about 100% of the full-load poweroutput of the GTG. In such an example, when an electric grid transientoccurs, the stored energy of the storage device 14 is used for transientprotection, such that the GTG 12 ramps, such as substantiallyinstantaneously and at least a portion of a stored energy of the storagedevice 14 is transferred to the electric grid. In the instance where theelectric grid 20 requires additional economic energy, the gas firedgenerator can be started and loaded without the use of the storagedevice 14.

FIG. 2 shows a plot 30 of one example of a hybrid energy system startprofile, according to the present disclosure. The values represented inFIG. 2 are merely for example purposes and are not limiting. Forexample, FIG. 2 illustrates the start of the GTG (12, FIG. 1) and thesubsequent ramping of the GTG in an EGT system configuration. In theplot 30, the y-axis represents power output in megawatts (MW) and thex-axis representing elapsed time in minutes. Although, specific poweroutput, power storage, and times are shown, they are to be understood asexemplary only and do not limit the current disclosure. The hybridenergy system plotted in plot 20 includes a storage device with anenergy storage capacity of at least about 10% of the full-load poweroutput of the GTG. Further in the example plotted in FIG. 2, the storagedevice includes an inverter-rectifier having at least 20% of thefull-load power output of the GTG 12.

At time T=0 minutes the hybrid energy system (10, FIG. 1) receives acommand, such as detection of a transient event, market event, or thelike, to start and ramp the GTG to a desired load 38 of 50 MW. In anexample, the desired load 38 is a desired load output for the hybridenergy system or the desired load output of the GTG. The desired load 38can be partial full-load output of the GTG or full-load output of theGTG. Further, as described above, the GTG is in the stand-by state. Asshown by line 32, the storage device (14, FIG. 1) discharges at least aportion of the stored energy capacity substantially simultaneously tothe delivery of a command to start the GTG. As shown in plot 30, a totalhybrid energy system output 36 is substantially equal to the storagedevice output 32 from time T=0 minutes to T=3 minutes. That is, thestorage device output 36 is equal to the total hybrid energy systemoutput 36 when the GTG output 34 is zero MW (e.g., initiating a startsequence). The storage device output 32 from time T=0 minutes to timeT=3 minutes follows a ramping profile (e.g., slope of 32) similar (e.g.,continually increasing toward the desired load 38) to that as if the GTGwere to ramp alone from an on-line mode and synchronized, such as atotal hybrid energy system output 36. However, unlike the ramping of anon-line GTG, the discharge of the storage device does not result in theproduction of emissions, including, but not limited, to air pollutants,such as greenhouse gases. Further, substantially simultaneously to thestorage device discharging at least a portion of its stored energy, theGTG initiates its start sequence, indicated by line 34.

As an example, shown by GTG output 34, the GTG generatorsynchronization, loading profile, and warm-up sequence is initiated atabout time T=3 minutes until about time T=4 minutes. As shown, at timeT=3 minutes the storage device reduces its output 32 as the GTG beginsto provide positive GTG load output 34 to the total hybrid energy systemoutput 36. The plot 30 illustrates a minimum standard for the rampprofile of the total hybrid energy system output 36. Alternatively, thestorage device output 32 can maintain a substantially constant positiveramp profile (e.g., slope of 32) from time T=3 minutes to time T=4minutes or can maintain a substantially constant storage device output32 (e.g., slope of zero). In an example, the total hybrid energy systemoutput 36 is continually increasing toward the desired load 38 or has aramp profile with a slope of zero for 1 minute or less while ramping tothe desired load output. At time T=4 minutes, the GTG has warmed-upsufficiently to continue ramping the output 34 to the desired GTG load38. Substantially simultaneously, the storage device reduces the storagedevice output 32 until it is no longer discharging, while maintaining acontinually increasing the hybrid energy system output 36 towards thedesired storage load 38. As shown in FIG. 2, in an example, a totalhybrid energy system is configured, such as the EGT configuration, tostart the GTG from the stand-by-state state to the full-load poweroutput and discharge at least a portion of the stored energy of thestorage device at a hybrid ramp rate that substantially matches a gasturbine alone ramp rate. Thus, the HMS integrates the GTG start timeinto the ramp rate of the output of the energy storage system such thatthe GTG start time is non-apparent in the total facility output. In anexample, the single composite power output response of the hybrid energysystem may transition from about −50 MW to about 100 MW.

In this manner, the EGT configuration can provide substantiallycontinuous and substantially immediate responses to electric gridtransients and contingencies without at least a portion of the undesiredattributes of unnecessary fuel burn, unwanted pollutants, and unrequiredenergy contributed by the typical gas fired generation units of thecurrent electric grid. For example, reducing unwanted pollutants mayinclude reducing the pollutant profile (e.g., pollutants produced perMW, time, or unit of fuel).

Enhanced Storage (ES)

In an example, the hybrid energy system (10, FIG. 1) is configured touse the GTG (12, FIG. 1) to supplement the storage device (14, FIG. 1),such as, for example, maintain a state of charge of the storage deviceduring operation of the hybrid energy system, such that the fasterresponding storage device is available to respond to an electric gridfrequency transient. In an example, a portion or all of the GTG outputmay be converted to DC and delivered to a DC bus of the storage device,such as the inverter-rectifier (15, FIG. 1), to allow for evenimprovement (e.g., faster) in the primary frequency response.Additionally, in an example the GTG is equipped with a frequencyresponse auto start capability for instances when the GTG is in thestand-by state. In an example, the hybrid energy system includes a wasteheat recovery generator.

The ES configuration includes, in an example, the stored energy capacityof the storage device approximately equal to or greater than thefull-load power output of the GTG. That is, the storage device at leasthas, in an example, approximately the same immediate power dischargecapability as the GTG when started and fully loaded. As describedherein, the storage device provides a short-term substitution of the GTGfull generation capacity. In an example, the stored energy capacity ofthe storage device is at least about 15 minutes, about 1 hour, about 1.5hours, about 2 hours, or about 4 hours or longer of power discharge ator beyond the full-load power output of the GTG.

FIG. 3 shows a plot 40 of one example of an operation, such asregulation output, of the hybrid energy system, such as managing a stateof charge of the storage device with the GTG, according to the presentdisclosure. The values represented by FIG. 3 and Table 1 are merely forexample and are not limiting. In the plot 40, the left y-axis representsMW and pertains to lines 44, 46, and 48; the right y-axis represents MWhand pertains to line 42; the x-axis represents time in minutes andpertains to each line 42, 44, 46, and 48. As shown in FIG. 3, the GTGoutput 46, from about time T=1 minute to about time T=7 minutes isapproximately a constant 25 MW. During this window of time (1 to 7minutes) regulation ramping 48 varies significantly and randomly. Inresponse to the varying regulation ramping 48, the storage devicesubstantially immediately responds likewise in its discharge 44. Forexample, from time T=3 minutes to time T=4 minutes the regulationramping 48 decreases and the storage device output 44 also decreases.This is accomplished by having the GTG output 46 in excess of therequired regulation output. The excess energy is diverted to chargingthe storage device to maintain its state of charge 42 relativelyconstant at around 100 MWh Similarly, when the regulation rampingincreases 48, for example from time T=4 minutes to time T=5 minutes, thestorage device output 44 increases the output to match the demand. Ascan be seen in FIG. 3, this relationship holds true even with theoverall hybrid energy system output increases from approximately 25 MWto approximately 44 MW. In an example, the storage device is configuredto respond (e.g., substantially simultaneously) before the GTG when theregulation demand is detected during operation of the hybrid energysystem. By maintaining the state of charge 42 of the storage device, thehybrid energy system is capable of substantially immediately respondingto operations, such as regulation, while the GTG is on-line.

As shown in FIG. 3, during fluctuations in regulation ramping 48, thestate of charge of the storage device 42 remains substantially constant,approximately 100 MWh. This is accomplished by the charging anddischarging of the storage device in response to each of the changes ofthe regulation ramping 48. Table 1 titled “Managing State of Charge withthe GTG in FIG. 3” corresponds to the plot 40 including state of charge42, storage device output 44, GTG output 46, regulation ramping 48. Asshown in Table 1, from time T=1 minute to time T=5 minutes, the desiredGTG output is 24 MW, allowing the GTG, assuming a 50 MW GTG for thisexample, to operate at half-power. However, at time T=5 minutes theregulation ramping increases to 43.4 MW. As such, the storage deviceoutput is substantially immediately increased to 19.4 MW to provideoutput in addition to the GTG output of 24 MW, so as to provide theregulation ramping output of 43.4 MW (e.g., 19.4 MW+24 MW=43.4 MW). Dueto the higher load requirements initiated by the regulation ramping attime T=5 minutes, the GTG output is increased to 40 MW from time T=6minutes to time T=10 minutes as shown by the positive slope of line 46in FIG. 3. During that GTG ramping time frame from time T=6 minutes totime T=10 minutes, the storage device continues to respond to anyregulation ramping. For example, at time T=6 minutes the regulationramping decreased to 21.9 MW. However, the GTG has already begunincreasing its output above 24 MW. The GTG output in excess of theregulation ramping output of 21.9 MW is provided to the storage deviceto maintain the storage device state of charge. For example, the storagedevice output is decreased to −18.10 MW (e.g., charging) while the GTGoutput is 40 MW, so as to provide the regulation ramping of 21.9 MW attime T=6 minutes (e.g., 40 MW+(−18.1 MW)=21.9 MW).

Further, as shown in Table 1, from time T=1 to time T=15 the totalregulation ramping output for the example was 9.12 MWh. Although thestorage device is configured to respond first to regulation ramping thetotal output for the storage device was 0.45 MWh, while the gas turbineoutput was 8.67 MWh. As shown by FIG. 3 and the corresponding Table 1below, the storage device does the fast acting regulation and the GTGmaintains the state of charge on the storage device so that the storagedevice continues to responding at fast rate without the charge of thestorage device being depleted.

TABLE 1 Managing State of Charge with the GTG in FIG. 3 Storage StorageDevice Device GTG Regulation Storage State of Output Output RampingDevice GTG Regulation Charge Time 44 46 48 Output Output Ramping 42(minute) (MW) (MW) (MW) (MWh) (MWh) (MWh) (MWh) 1 20.00 24.00 44.00 0.330.40 0.73 99.67 2 −25.00 24.00 −1.00 −0.42 0.40 −0.02 100.08 3 −2.2024.00 21.80 −0.04 0.40 0.36 100.12 4 −30.00 24.00 −6.00 −0.50 0.40 −0.10100.62 5 19.40 24.00 43.40 0.32 0.40 0.72 100.30 6 −18.10 40.00 21.90−0.30 0.67 0.37 100.60 7 44.30 40.00 84.30 0.74 0.67 1.41 99.86 8 −50.0040.00 −10.00 −0.83 0.67 −0.17 100.69 9 20.00 40.00 60.00 0.33 0.67 1.00100.36 10 −5.00 40.00 35.00 −0.08 0.67 0.58 100.44 11 −35.00 40.00 5.00−0.58 0.67 0.08 101.03 12 43.20 40.00 83.20 0.72 0.67 1.39 100.31 1343.80 40.00 83.80 0.73 0.67 1.40 99.58 14 −6.80 40.00 33.20 −0.11 0.670.55 99.69 15 8.60 40.00 48.60 0.14 0.67 0.81 99.55 Total MWH 0.45 8.679.12

EGT, ES, Battery Only, and GTG Only Comparison

Table 2 entitled “Hybrid Energy System Example Configurations” belowprovides an example of an EGT configuration, an ES configuration, aBattery storage only configuration, and a GTG only configuration. Asshown in Table 2, the EGT configuration is a substantial improvementover the GTG only configuration in that the operating range is extendedat the lower end by approximately 50% and provides for emissions-free,electric grid reliability products until such time as the GTG isactually needed to respond to a reliability event. As further evidencedby Table 2, the ES configuration is a substantial improvement over thebattery only in that its operating range is extended by approximately50% at the upper end and provides for extended operating times.

TABLE 2 Hybrid Energy System Example Configurations Enhanced Battery GasGTG Enhanced Storage Turbine (EGT) Storage (ES) Only Only Pmin 0.1 MW−50 MW −50 MW 25 MW Pmax 49 MW 99 MW 50 MW 49 MW Primary 49 MW 99 MW 50MW 24 MW Frequency Response Emissions-Free 10 MVAR 50 MVAR 50 MVAR 0MVAR Voltage Regulation Emissions-Free 49 MW 99 MW 50 MW 0 MW SpinningReserve Energy Output 49 MW 99 MW for 4 50 MW 49 MW for hours, 49 MW for4 for unlimited for unlimited hours unlimited hours hours hours EnergyHeat Rate, 9,850 Market heat Market 9,850 BTU/kWh rate capped at rateapproximately 12,000

ES Transient Response

FIG. 4 illustrates a transient response of an ES hybrid energy systemconfiguration having a 50 MW GTG and a storage device having a 50 MWstored energy capacity compared to a 100 MW gas turbine only system. TheES hybrid energy system configuration is used for example and should notbe construed as limiting the present subject matter to only such aconfiguration. FIG. 4 illustrates a plot 50 of a 0.3 hertz (Hz)frequency drop when a hybrid energy system and a gas turbine only systemare on-line. As shown in plot 50, the ES hybrid energy system output 52provides a faster primary frequency response than the 100 MW gas turbineonly system output 54. As designed by industry standards, improvedprimary frequency response from the ES hybrid energy system is worthapproximately three times that of an average synchronous GTGre-dispatched. As such, FIG. 4 illustrates that the ES hybrid energysystem provides at least two times the frequency regulation service thanthe 100 MW gas turbine only system.

During periods when an electrical grid is operating within its normaloperating limits, the gas fired generation system can remain off-line,such that primary transient protection can be from a storage system. Ifthe storage system is required by the electrical grid to operate fortransient protection, the gas fired generator (e.g., gas turbine) canstart, such as substantially instantaneously, and at least a portion ofa storage load of the storage system can be transferred to the gas firedgenerator upon synchronization of the gas fired generator. The storageoutput of the energy storage system does not need to be additive to thegas turbine output, but rather provides (e.g., substantiallyinstantaneously) output until the gas turbine can deliver the necessaryoutput. That is, the energy storage system can be slaved to the gasfired generation output such that the energy storage system dischargesthe difference between the facility Pmax and the actual gas firedgeneration output, on a net basis.

In FIG. 5, another example of a hybrid generation grid support systemresponse time plot is shown, with the y-axis representing power outputin megawatts (MW) and the x-axis representing elapsed time in minutes.Although, specific gas turbine power output, storage power output, andtimes are shown, they are to be understood as exemplary only and do notlimit the current disclosure. As shown, from time 0 minutes to time 5minutes the gas turbine's generator is in an off-line condition (60).During the same time period, the energy storage system produces 50 MW ofenergy output (64). Although FIG. 5 illustrates the energy storagecapacity equal to the total facility output, embodiments are not solimited. For example, the energy storage capacity can be greater thanthe total facility output.

In the example illustrated in FIG. 5, at time 0 minutes a transientevent occurs. As described herein, substantially instantaneously upondetection of the transient event the HMS may control the energy storagesystem to substantially immediately respond with its full output,drawing power from the energy storage system while the gas turbineinitiates its start sequence (60). The gas turbine generatorsynchronization and loading profile (62) can be seen in FIG. 5 beginningat time 5 minutes. Once the gas turbine has completed its start sequenceand is synchronized (time 5 minutes), the HMS will reduce the load drawnfrom the energy storage system at a rate that is inversely proportion tothe net gas turbine generator output. That is, the HMS may control thepower output by the energy storage system so that the slopes of theoutput of the energy storage system and the gas turbine generator fromtime 5 minutes to time 10 minutes are substantially equal but opposite.Thus, at time 10 minutes when the gas turbine output is substantiallyequal to the total facility output (66) there is no longer any outputfrom the energy storage system (68). In this manner, this method canprovide substantially continuous and substantially immediate responsesto a system transient and contingencies without at least a portion ofthe undesired attributes of unnecessary fuel burn, unwanted pollutants,and unrequired energy contributed by maintaining the gas turbinegenerator spinning in a hot standby mode as is typical for current gasfired generation units providing standby power for the grid.

Various embodiments enable the hybrid energy system to be operated in anumber of configurations and manners to provide operators with economicadvantages. For example, the HMS may use a life-cycle cost envelope thatincludes the financial impact of starting, cycling, and running the gasturbine at minimum load. For example, the variable operating cost ofrunning the hybrid energy system at its super-low Pmin can be used topartially offset the avoided cost of buying parasitic load at retailrates and the value of spinning or flexible capacity.

In electric markets with variable pricing, the feed-forvvard loop of theHMS may take inputs from at least one of Day-Ahead (DA) market awards,schedules, prices, DA load forecasts, Variable Energy Resource (VER)forecasts, GT/battery life-cycle, and operational envelopes, so as toprovide an initial DA Expected Delivery Schedule (DA EDS), asillustrated in FIG. 6. The DA EDS may then be updated as required withinformation :from the Real Time market (RI EDS) as illustrated in FIG.7. The RT data may have a time horizon of one hour, two hour, threehour, four hour, five hour, six hour, seven hour, eight hour, nine hour,ten hour or more, which will run periodically, such as anywhere fromabout 5 seconds to 20 minutes or more, to correct the plan based upon atleast one of the RT market awards, schedules and prices, RI loadforecasts and RI VER forecasts and the GT/battery fe-cycle andoperational envelopes at intervals, such as about 5 hr, 4 hr, 3 hr, 2hr, 1 hr, 15 minutes, or 5 minutes.

The initial expected energy schedule can be modified in real time by thefeedback loop of the HMS, which takes inputs from the Operator or fromthe market awards for product type (e.g., energy, ancillary services,flex-ramp) which can govern at least one of the applied ramp rates,Dispatch Operating Target (DOT), 15 minute trajectory, plant controlsystem for the current operator set-point for net plant output, batterySOC, GTG output, and actual plant net output. Once again, the HMS willbe directed by the operator in response to market instruction from thebids and schedules per the off- take agreement or RT instructions perthe Operator and the optimization effort may ensure the unit ispositioned to ensure any contractual terms are met while minimizingcapital costs, for example.

In an example, the HMS may deliver DA and RT availability and pricinginformation for energy and capacity products to the SchedulingCoordinator (SC).

Life-cycle costs can vary. For example, faster ramp rates can cost morethan slower ramps. Therefore, the HMS may match the specific needs on alowest emissions or least cost basis. The hybrid facility may include anumber of ramping profiles depending whether the gas turbine is runningor not and whether the response is from the GTG only, battery only, or acombined GTG and battery response. The fastest ramp rates may bereserved for primary frequency response and are a function of the gasturbine governor and battery inverter outside of and at a higherpriority to the HMS optimizations. For example, Table 3 lists 25exemplary ramping profiles, and FIG. 8 illustrates example ramptrajectories.

TABLE 3 Exemplary Ramping Profiles Battery & Battery GTG only GTG and GTRamp Rate Battery GTG only from from from GT MW/Min only from S/D PminGTG S/D Pmin Lowest 3.33 3.33 3.33 6.67 6.67 Low 12.50 3.33 5.00 15.8317.50 Med 25.00 5.00 10.00 30.00 35.00 High 37.50 7.50 15.00 45.00 52.50Highest 50.00 10.00 20.00 60.00 70.00

Primary frequency response may be dampened for a portion or the entirefacility by the Power System Stabilizer (PSS). For all other products,the HMS may restrict the use of the gas-fired generation to only thoseperiods where it is needed to support grid reliability or respond touser defined economic signals, The HMS may start and stop the gasturbine as required is such a way as to keep the output linear asrequired.

The feedback loop of the HMS receives, as its primary inputs, the RTinstruction from the Operator and the RT plant net output. A finaloptimization may be performed using a time horizon, such as a 5 minutetime horizon, a 10 minute time horizon, a 15 minute time horizon, or a20 minute or longer time horizon, as shown in FIG. 9. This finaloptimization may allow the HMS to correct for any deviations from the RTEDS and will issue the final outputs to the battery inverters and gasturbine necessary to meet the Operator instruction. During thisoptimization, the HMS will make the final decision and. issueinstructions to start and stop the gas turbine, charge the battery, andramp the plant at specified ramp rates.

The batteries may be charged by the gas turbine during periods where anull output from facility is desired but the intertemporal value of gasfired generation will be needed in a later period either for reliabilityor economic energy. This null period can occur somewhat frequently forshort durations of time, such as about 5 minutes to about 15 minutes,when the facility is at full load. If desired, the hybrid facility mayrespond to a short real time price drop such as those produced byvariations from renewable resources, or overlapping ramps of thermalgeneration by simply directing all GT power to the battery, avoiding thecycle costs on the GT, until the event has concluded.

The HMS may optimize the energy delivery and. SOC in such a way as todeliver energy in the least cost manner, but also for the longest periodof time. For example, the HMS may use the RT EDS, current day gas pricesand current RT energy prices to determine if a dispatch instruction topart load (50% for example) should be met by the battery only, the GTonly, or a combination of battery and GT. Limiting the battery output inone interval will extend its ability to deliver in the next interval. Inthis example, the facility energy pricing may be viewed as eitheraggregate or individual pricing of battery and GT over the time horizon.

In another example, the HMS may determine whether the transition energyproduced by the GT during its normal ramping should be delivered to thegrid or to the battery in order to extend the battery range. This may beaccomplished on both positive and negative ramps.

Products provided by the hybrid energy system may include: inertia orprimary frequency response, voltage support, energy, capacity forflexible ramping (as required for renewable integration), preventive orcorrective capacity, and ancillary services.

The HMS may manage the facility output based on a number of factors,including but not limited in scope or order:

-   -   1. Grid reliability        -   a. Local Grid Reliability needs            -   i. Primary frequency control            -   ii. Secondary frequency control            -   iii. Voltage support            -   iv. Preventive Capacity (N-1)            -   v. Corrective Capacity (N-1-1)        -   b. Area Grid Reliability            -   i. Ramping energy            -   ii. Regulation            -   iii. Spinning Reserve    -   2. Emissions Reductions        -   a. The hybrid operating range allows the maximum headroom            for green renewables operating as Variable Energy Resources            (VER) to produce at their maximum output without            curtailment. The hybrid facility may respond with negative            or positive output to provide:            -   i. Flexible ramping up during periods when VER output                dips.            -   ii. Flexible ramping down during periods where VER                output increases.    -   3. Economic Energy.        -   a. The hybrid operating range allows the maximum headroom            for the lowest cost energy by responding in real time with            negative or positive energy prices based upon:            -   i. Arbitraged storage price—storage only output.            -   ii. Aggregate arbitraged storage price and gas-fired                heat rate—storage and gas-fired output.

iii. Gas-fired heat rate—gas-fired output only. iv. Aggregate gas-firedheat rate gas-fired and storage output when storage was charged with gasfired generator.

The HMS may optimize on the maximum usage of the storage system thatfacilitates the minimum amount of gas burned from the gas turbine tomeet the priorities of: 1) reliability, 2) emissions reductions, or 3)economic energy. This decision process may aid in meeting an off-takeagreement or other contractual terms and conditions, while protectinginvestment (e.g., capital) in the hybrid energy system. Thisoptimization may include at a minimum, the following inputs:

-   -   1. Primary frequency response demand from plant sensors and        power system stabilizer.    -   2. Local area inertia need—discrete out of market schedule or        dispatch by ISO,    -   3. Preventive capacity (N-1)—discrete out of market schedule or        dispatch by ISO.    -   4. Corrective capacity (N-1-1)—discrete out of market schedule        or dispatch by ISO.    -   5. Economic market signals.        -   a. Day ahead and Real Time market pricing for energy and            ancillary services.        -   b. Day ahead Real Time load forecasts.        -   c. DA and Real time Variable Energy Resource (VER)            forecasts.        -   d. Flexible ramping—intertemporal price signal to cover net            load changes caused by VER.    -   6. Gas Prices Variable operating costs of hybrid facility.    -   7. Life cycle maintenance cost constraints—storage system.        -   a. Life cycle maintenance cost constraints—gas-fired            generation.

EXAMPLES

Example 1 can include subject matter (such as an apparatus, a method, ameans for performing acts, or a machine readable medium includinginstructions that, when performed by the machine, that can cause themachine to perform acts), such as a hybrid energy system, comprising: agenerator step-up transformer; a gas turbine generator (GTG) configuredto provide a full-load power output; and a storage device configured tostore energy, wherein the GTG and the storage device are electricallyco-located on a low side of the generator step-up transformer.

Example 2 can include, or can optionally be combined with the subjectmatter of Example 1 to optionally include wherein the GTG is a faststart GTG.

Example 3 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1 or 2 to optionallyinclude wherein the storage device is configured to be charged by anelectric grid if a grid market price is lower than a GTG charging cost.

Example 4 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-3 to optionally includewherein the storage device is configured to be charged by the GTG if aGTG charging cost is lower than a grid market cost.

Example 5 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-4 to optionally includewherein the hybrid energy system is configured to start the GTG from astand-by state and ramp the GTG to a desired power output of the hybridenergy system in about 20 minutes or less, wherein the desired poweroutput of the hybrid energy system is not greater than the full-loadpower output.

Example 6 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-5 to optionally includewherein the hybrid energy system is configured to ramp the GTG inresponse to a frequency disturbance.

Example 7 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-6 to optionally includewherein the GTG is off-line in the stand-by-state.

Example 8 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-7 to optionally includewherein the storage device is configured to be charged by an electricgrid.

Example 9 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-8 to optionally includewherein the storage device has as stored energy capacity at least about5% of the full-load power output up to about 100% of the full-load poweroutput.

Example 10 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-9 to optionally includewherein the storage device includes an inverter-rectifier having storedenergy of at least about 10% of the full-load power output.

Example 11 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-10 to optionally includewherein the total hybrid energy system is configured to start the GTGfrom the stand-by state to the desired power output of the hybrid energysystem and discharge at least a portion of the stored energy of thestorage device at a hybrid ramp rate that substantially matches in agas-turbine alone ramp rate.

Example 12 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-11 to optionally includea ramping profile of the hybrid energy system continually increasesuntil the desired power output of the hybrid energy system is obtained.

Example 13 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-12 to optionally includewherein a state of charge of the storage device is configured to varyless than 5% during operation of the hybrid energy system.

Example 14 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-13 to optionally includewherein a stored energy capacity of the storage device is at least equalto the full-load power output of the GTG.

Example 15 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-14 to optionally includewherein the stored energy capacity of the storage device has at leastabout 1 hour of stored energy discharge beyond the full-load poweroutput of the GTG.

Example 16 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-15 to optionally includewherein the storage device is configured to respond before the GTG whenan event is detected during the operation of the hybrid energy system.

Example 17 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-16 to optionally includewherein the hybrid energy system is configured to respond to an electricgrid demand.

Example 18 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 1-17 to optionally includewherein hybrid energy system is configured to respond to the electricgrid demand without producing any pollutants.

Example 19 can include subject matter (such as an apparatus, a method, ameans for performing acts, or a machine readable medium includinginstructions that, when performed by the machine, that can cause themachine to perform acts), such as a hybrid energy system, comprising: agenerator step-up transformer; a gas turbine generator (GTG) configuredto provide a full-load power output and having a minimum power output ofless than 5% of the full-load power output; and a storage deviceconfigured to store energy, wherein: the GTG and the storage device areelectrically co-located on a low side of the generator step-uptransformer, and a stored energy capacity of the storage device is atleast about 5% of the full-load power output up to about 100% of thefull-load power output.

Example 20 can include subject matter (such as an apparatus, a method, ameans for performing acts, or a machine readable medium includinginstructions that, when performed by the machine, that can cause themachine to perform acts), such as a hybrid energy system, comprising: agenerator step-up transformer; a gas turbine generator (GTG) configuredto provide a full-load power output; and a storage device configured tostore energy, wherein: the GTG and the storage device are electricallyco-located on a low side of the generator step-up transformer, thestorage device is configured to be charged based on at least one marketfactor, and the hybrid energy system is configured to provide asubstantially emissions free ramping of energy.

Each of these non-limiting examples can stand on its own, or can becombined in any permutation or combination with any one or more of theother examples.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In the event of inconsistent usages between this document and anydocuments so incorporated by reference, the usage in this documentcontrols. In this document, the terms “a” or “an” are used, as is commonin patent documents, to include one or more than one, independent of anyother instances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The term “substantially simultaneously” or “substantially immediately”or “substantially instantaneously” refers to events occurring atapproximately the same time. It is contemplated by the inventor thatresponse times can be limited by mechanical, electrical, or chemicalprocesses and system. Substantially simultaneously, substantiallyimmediately, or substantially instantaneously can include time periods 1minute or less, 45 seconds or less, 30 seconds or less, 20 seconds orless, 15 seconds or less, 10 seconds or less, 5 seconds or less, 3seconds or less, 2 seconds or less, 1 second or less, 0.5 seconds orless, or 0.1 seconds or less.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, in an example, the code can be tangiblystored on one or more volatile, non-transitory, or non-volatile tangiblecomputer-readable media, such as during execution or at other times.Examples of these tangible computer-readable media can include, but arenot limited to, hard disks, removable magnetic disks, removable opticaldisks (e.g., compact disks and digital video disks), magnetic cassettes,memory cards or sticks, random access memories (RAMs), read onlymemories (ROMs), and the like.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. .sctn.1.72(b), to allow the reader to quickly ascertainthe nature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A method for controlling a hybrid energy systemincluding a step-up transformer, a gas turbine generator configured tooutput alternating current (AC) power to the step-up transformer, anenergy storage system, an inverter-rectifier configured to receiveddirect current (DC) from the energy storage system and output AC powerto the step-up transformer, and a hybrid management system (HMS) coupledto the gas turbine generator, energy storage system andinverter-rectifier and configured to govern a ramp rate of net plantoutput, the method comprising: determining, by the HMS, an expecteddelivery schedule from at least one of market awards and schedulesprovided by an operator; determining, by the HMS, timing for chargingthe storage device based upon the expected delivery schedule;determining, by the HMS, a least cost method of delivering energyproduced by the hybrid energy system based upon the expected deliveryschedule; governing, by the HMS, a charge state of the energy storagesystem based upon the determined least cost method of delivering energyproduced by the hybrid energy system; starting or stopping the gasturbine generator based upon the determined least cost method ofdelivering energy produced by the hybrid energy system and on real timeinstructions from the operator; and governing, by the HMS, a ramp rateof net output power of the hybrid energy system when starting the gasturbine generator.
 2. The method of claim 1, wherein: determining, bythe HMS, the least cost method of delivering energy produced by the gasturbine generator based upon the expected delivery schedule comprisesshutting down the gas turbine generator when no net output power is tobe delivered; and governing, by the HMS, a ramp rate of net output powerof the hybrid energy system when starting the gas turbine generatorcomprises responding , by the HMS, to an increasing desired loadtransient event when the gas turbine generator is initially stopped bydischarging a portion of the stored energy capacity of the energystorage system while the gas turbine generator is starting such that thenet output power of the hybrid energy system follows a ramping profilecontinuously increasing toward the desired load at a hybrid ramp ratethat substantially matches a gas-turbine generator ramp up rate as ifthe gas turbine generator were running in an on-line mode at the startof the transient event.
 3. The method of claim 1, wherein governing, bythe HMS, a charge state of the energy storage system based upon thedetermined least cost method of delivering energy produced by the hybridenergy system comprises charging the energy storage system by anelectric grid if a grid market cost is lower than a gas turbinegenerator charging cost.
 4. The method of claim 1, wherein governing, bythe HMS, a charge state of the energy storage system based upon thedetermined least cost method of delivering energy produced by the hybridenergy system comprises charging the energy storage system by the gasturbine generator if a grid market cost is lower than a gas turbinegenerator charging cost.
 5. The method of claim 1, wherein governing, bythe HMS, a charge state of the energy storage system based upon thedetermined least cost method of delivering energy produced by the hybridenergy system comprises the HMS discharging the energy storage system torespond to an increased grid power demand before the gas turbinegenerator can respond and to operate the gas turbine generator at apower level greater than the grid power demand sufficient to rechargethe energy storage system so that the state of charge of the energystorage system varies less than 5% during operation of the hybrid energysystem.